Filler solder

ABSTRACT

Filler solder for use on automobile bodies and the like and containing essentially the following constituents within the proportion ranges hereafter set forth:   The arsenic plus antimony in the solder should total at least 3.5% but not exceed 6%. The solder is free of hard tin-arsenic platelets and free of an undesirable grittiness, which is attributed to the elimination of the tin-arsenic platelets. Due to its freedom from grittiness, the filler solder is readily applied to automobile bodies and the like for filling certain crevices and spaces in the sheet metal bodies as a smoothsurfaced deposit.

United States Patent 1 1 Di Martini et a1.

[ 1 FILLER SOLDER [75] inventors: Carl R. Di Martini, Piscataway;

Michael Myers, New Brunswick. both of NJ.

[73] Assignee: Asarco incorporated, New York.

[22] Filed: Jan. 9, 1974.

[21] Appl. No.: 432,107

[52] US. Cl. 75/166 C; 75/166 B [51] C22C 11/08; C22C 11/10 [58] Field of Search 75/166 C. 166 B [56] References Cited UNITED STATES PATENTS 1,807,788 6/1931 Kemp 75/166 c 2,298,237 10/1942 Smith et al....... 75/166 C 2.351.477 6/1944 Bouton et a1. 75/166 C 2.370.439 2/1945 Beard 75/166 C 2.678.341 5/1954 Stoertz... 136/65 3,197,862 8/1965 Harvey 29/528 Dec. 2, 1975 Primary ExaminerL. Dewayne Rutledge Assistant Examiner-E. L. Weise Attorney. Agent. or Ft'rm-R. J. Drew; E. J. Schuffer [57] ABSTRACT Filler solder for use on automobile bodies and the like and containing essentially the following constituents within the proportion ranges hereafter set forth:

1 by Weight Antimony 1.5 to 5.3 Arsenic 0.7 to 2.5

'n maximum 11.211 Lend substantially the remainder 6 Claims, 5 Drawing Figures U.S. Patent Dec. 2, 1975 Sheet 1 of4 3,923,501

US. Patent Dec. 2, 1975 Sheet 2 of4 3,923,501

M920 T/N-wqESEN/C LHT'LE TS U.S. Patent Dec. 2, 1975 Sheet 3 of4 3,9235% FIG. 4

U.S. Patent Dec. 2, 1975 Sheet-1 0m FIG. 5

FILLER soaosa ble to the sheet steel of automobile bodies and the like as a substantially smooth-surfaced deposit and without the formation of pits and pops in the subsequent painting and baking-operations.

2. Description of the Prior Art Lead base filler solder alloy hasbeen applied to automobile bodies by partially melting the solder. stirring the partially melted solder slightly. and then applying the solder to the heated and tinned automobile body as a viscous"mush.. The 'solidus temperature. liquidus temperature. and volume fraction of liquid, as a function of temperature. are significant factors in determining ease of application of the solder. For example. a solder alloywith a very narrow freezing range would be difficult to control to a desirable volume fraction of liq-.

aid to providethe desired fluidity of plasticity for easy application. Alead base filler. solder presently being employed on automobile bodies has the nominal composition of Pia- 5% Sb -l Sn-0.5%As. and is about 25% eutectic by volume with a" 38C.freezingrangessuch a filler'solder is' disclosed in U.S. Pat. No. 3.l97,862 which discloses'body fillersolders containing about 2 2% arsenic. and about (N94 to about 2% tin. the tin content being about one-fifth of the antimony content. U.S. Pat. No. 2.35 1.477 discloses a wiping solder alloy containing 61-67% lead. 20-26% bismuth. l0-i694 tin. 0.05-0.l5% arsenic and 0.l-l7t antimony. together with incidental impurities. U.S. Pat. No. 2.439.068 discloses solder compositions consisting of about tin. from above 0.005% to about 0.5% zinc. from about 0.5% to about 1.75% antimony. balance substantially all lead. U.S. Pat. No. 2.l9l.624 relates to wiping solders containing between about 30% and about 40% tin. between about 0.02% and about 0.l5% arsenic. remainder lead together with incidental impurities. U.S. Pat. No. 2.290.237 is concerned with lead base coating alloy consisting of U.2%3% antimony. 0270-57: zinc. lX -lOib tin. balance lead. with the zinc and lead totala ling not less than 3%.

4.5% to 6% antimony. 0.3% to 0.6% arsenic. 0.25% to was gritty at the application temperature and difflcult to apply.'The undesirable grittiness of 'the filler solder was of such nature that onccouid actually feel the hard grit particles in the soft, semi solid mass of filler solder. The workers applying the. filler. solder to the automobile bodies complained about thegrittiness of the soldcr.'and that the gritty solder was not easily'applicable to the automobile bodies asa smooth-'surfaeeddeposit. Another. customer complaint regarding the grittyflller solder has been that the gritty solder'alloy. solidified in OBJECTS OF THE INVENTION One object of the invention is to provide a new and improved filler solder for use on automobile bodies and the like which is free of grittiness. and hence is readily applicable to the sheet metal automobile bodies and the like as a smooth surfaced deposit.

Another object of the invention is to provide a new and improved filler solder for use on sheet steel automobile bodies and the like, which is free of grittiness due to its being free of an undesirable tin-arsenic phase and. more specifically. free of undesirable hard tinarsenic platelets.

Another object is to provide a new and improved filler solder for use on automobile bodies which eliminates or substantially eliminates the undesirable pit and pop formation after painting and baking.

An additional object is to provide a filler solder characterized by possessing a ratio of volume fraction of solid (dendritic lead) to volume fraction of liquid at application temperatures such as to possess the desired plasticity or fluidity of the tiller solder for easy. troublefree application to automobile bodies and the like.

A further object is to provide a filler solder characterized by having a wide freezing range which facilitates obtention of the desired ratio of volume fraction of dendritic lead (solid) to volume fraction of liquid at the application temperature. such that the filler solder such manner on thetlau t'omobile body as to result in the formation of pits'andpops in thesolderinsub'sequent painting and baking operations. One plausible expiana;

tion advanced fortheformatlon of the-pitsand pops has been the dislodging'of 'the-grit p'artieles frorn thesolder surface afterjapplieatlon ofthe solder. leaving pits or indentationskAir is entrapped or'oecluded in the pits bythe paint"fil'mduring the paintin'g.' and the ex pansion-of theheat"ed occluded airidurin'gthe baking I results in tiicfforrn'ati on of the pops U.S. -Pat."No." 2.370.439 discloses a-lead y fillerailoy for use ona utomotive vehicles and comprising between about 2 Sand 7%} antimony."between about' 0.04. and

about'0.i arsenie,"betwe en' about 0.02%. and about 0.07% copper. between about l'llyandmbout 4% tin.

balance substantially alllead. U.S.Pat; No. 3.644.115.

relates to solder tillernmetal alloysco'm'prising about 0.005 to 0.2% aluminum. about O.2jto 99% tin. remainder lead. U.S. Pat. No. I,807.788ldiscloses.lead base alloys of'greater than normal/hardness comprising possesses the desired plasticity at the application temperature for easy. trouble-free application to automo- SUMMARY OF THE INVENTION We have found that the aforementioned grittiness and difficult application problems are minimized or elrninated and all of the aforementioned objects attained by a filler solder alloy containing essentially the following constituents and in proportions within the following critical proportion ranges:

K by Weight Antimony A rse nie Tin Lead The total of arsenic plus lead in the filler solder is critically at least 3.5% and not in excess of 6%. The microstructure of the "alloy is free or-substantially free of a tin-arsenic phase and free or substantially freeof hard tin-arsenic platelets. and we attribute the improvements provided by the tiller solder of. this invention in being free or substantially free of grittiness and hence readily applicable to sheet metal automobile bodies and the like as a smooth surfaced deposit to the absence of the tin-arsenic phase. and more specifically to the absence of the hard tin-arsenic platelets.

The freedom or substantial freedomfrorn grittiness and the ease of 'ap'plicatlonto automobile bodies and the like as a smooth surfaced deposit providedby the body filler solder of this invention. as well as the elimination or'substantial elimination of the pits and also the pops after painting and baking provided by ,the filler solder herein were unexpected results. The 0.20% maximum of tin is critical in the new and improved filler solder of this invention for the reasons that with amounts of tin in excess of 0.20% the undesirable tin-arsenic phase and thcgrittiness occurs in the solder. The 0.7%to 2.5% range of arsenic is also critical in the filler solders'of this invention for the reasons that with an amount of arsenic in the solder much in ex cess of 2.5%. there is too great a volume fraction of liqaid at the applicationtemperature. i.e; there is toomuch liquid in the filler solder at the application temperature relative to the solidtherein. Dueto the too' great volume fraction of liquid.'the filler solder is too i.e. too much or too little liquid phaseis present in the solder at the application temperaturerelative to the 4 taining lead. arsenic and antimony. Consequently. excessive volume fraction of liquid phase is present in the filler solder at the application temperature in the range of about 245C. to about 285C. and the filler solder is too fluid or liquid and does not have the desired plasticity for application to the automobile body. Alloys of this invention which contain less than a total of 3.5% of arsenic and antimony contain insufficient low melting phaseis) containing lead. arsenic and antimony. and too much relatively high melting phase (dendritic lead). As a result. there is too little volume fraction oi v liquid phaseand too much volume fraction of solid phase (dendritic lead) present at the application temperature in the range of about 245C. to 285C. and the filler solder does not have sufticient fluidity or iiquidityto possess the desired plasticity for application to automobile bodies.'Furthcrmore. the presence of a total of arsenic plus antimony of less than 3.5% in the alloys of this invention results in liquidus temperatures considerably higher than 285C. and in excess of 300C.. which are higher liquidus temperatures than desirable.

The filler solders herein are characterized by a wide freezing range corresponding to a liquidus of about 285C. and a solidus of about 245C.

The filler solders of this invention are characterized by containing about 70 to about 80% by volume dendritic lead, which is the solid phase. and about 30 to about 20% by volume liquid phase. By virtue of containing such amounts of solid phase and liquid phase. the filler solders herein possess a desired plasticity at the application temperature for easy. trouble-free application to automobile bodies and the like. This corresolid therein. or an undesirably high liquidus tempera ture. By reason of the excessive orinsufficientfliquid phase being present. the filler solder is eitherv too liquid or too solid respectively andis not suitable for application to automobile bodies due to not having a proper plasticity for such application. The l.5% -5.3% of antimony is critical in the filler solders of this invention for the reason an amountiof antimony much above 5.3% cuts down the freezing range of the solder excessively and results in too narrow a'freezing range. With the narrow freezing range. itismore difficult to obtain the proper ratio of volume fraction ofdendritic lead (solid) to volume fractionof liquid ,such'as to'attain aflsuitable or proper. plasticity-in; the.;filler solder. at theapplica-;-

tion temperature. for application to'automobile bodies.

Furthermore. an I amount of antimony much: above 5.3% in the solder results inanexcessiveyolume fraction of liquid in 'thetsolder at the-application temperature. i.c. the solder is too liquid atthe application.tem-

perature to havethe pro'per plasticityfor'application to automobile bodies. A. .quantity. of. antimony much below l.5%in the filler solder herein results in an insufficient volume fraction of liquid phase therein. and the filler solder is too solid and does not have the desired sponds to a ratio of volume fraction of solid phase (dendritic lead) to volume fraction of liquid phase ining agent and, when utilized. is added to the solder alloy herein in typical amounts of about 0.003% to aboutO. 004% by weight of the sulfur. based on total alloy composition. The grain refiner is added to the solder alloy herein usually by being added to the molten alloy priorlto supplying the molten alloy into a mold or molds The. fil ler "sold er 'of thisinvention is produced by a method involving-preparinga molten alloy containing essentially; by weight. 1.5% to 5.3% antimony. 0.7% to jor supplied-into a mold or molds. ordinarily a metal ume fraction of lowineltingsecondary-phase) eonmold or molds,' and the'alloy cooled to below its solidus temperature.-The resulting solidified filler solder cast- The cooling ofthe filler solder alloy in the mold or molds is rapid and at a rate in excess of. 20F. per second above the liquidus temperature of the alloyand at a rate in excess of 6F. per second in the temperature range between the liquidus and solidus temperature. of

the alloy.

The molten alloy can be cast by any suitable casting procedure including continuous and non-continuous or static casting. For example. the molten alloy can be cast continuously in a wheel mold. such as a vertical wheel mold or a horizontal wheel mold..sueh as is dis closed in U.S. Pat. No. 3.197.862 wherein an annular copper mold is formed as an'annular groove in-the upper surface of a rotttble wheel. in the last-mentioned horizontal mold. a'cooling waterjacket is provided within the wheel portion for cooling the solder alloy at the rapid rate hereinbefore disclosed. in casting in a 6 ducc their cross-sectional areas 75% or more. in a conventional press-extrusion apparatus. The solder strip is cut into predetermined lengths by means of a conventional cutting blades.

The fillersoldcr alloy bars or lengths have a typical cross section of- A X a inch.

A plurality of alloys were prepared of the compositions set forth in the table hereinafter set forth. The alloys were cast and microstructural analysis conducted on the alloys. The microstruetural analysis included light and Scanning Electron Microscopic observation. as well as X-ray anaiysis.'l.ight optics were used to determine the form and. with certain alloy. relative amount of the priniury phase. Scanning Electron Microscope and microprobe work was employed to determine the components and morphology of the phases. X-ray procedures were employed to determine the exact nature of the tin-arsenic phase found in the tinbearing alloys. The liquidus and solidus points were also determined for each alloy. The results are set forth in the table which follows:

Volume Ratio of Higher Melting Dcndritic Lead to Allo Primary Phase Lower Melting No. Pb i Sb 1' As Z Sn T ,'C T,.-'C ATC (Percentages by Volume) Secondary Phases l Balance 5.0 0.5 [.5 280 242 38 Pb dendrites. 75% SmAs, 2 4.0 L5 L5 320 242 78 SmAs;

3 3.0 2.5 L5 320 242 78 SmAs, 4 0.90 L05 0 302 245 57 Pb dendrites. 92% i l.47:l 5 8.90 L08 0 253 245 8 No Pb dendrites observed 6 8.0 1.50 0 255 245 l0 No Pb dendrites observed 7 L98 L90 0 285 245 Pb dendrites. 74'; 2842i 8 6.9 2.07 O 255 245 ID No Pb dendrites observed 9 5.24 2.30 264 245 I9 No Pb dendrites observed to v 1.0 2.9" .0 w 285 245 4o Pb dendrites. 30% v 0.4m ll [.5 2.9 0 282 245 37 No Pb dendritesohserved l2 2.] 2.9 0 27B 245 33' Pb dendrites. l3Z' 0.l4:l l3 5.34 v 4.50 278 24S 33 i,.. As-Sbcrystals. No Pb :dendrites observed i4 213 4.90 V Ni 245 46 As-Sbcrystals. No Pb I dendrites observed l5 2.0 2.0 0.0l 282 245 37 Pb dendrites. 74% 2.84:l l6 2.0 2.0 0.05 282 245 37 Pb dendrites. 74% 2.84zi l7 2.0 2.0 0.25 282 245 37 Pb dendrites. 74% SmAs, l8 2.0 2.0 L0 -322 24$ 77 Sn.As,

T, Liquidus Temperature T, Solidur Temperature. f

vertical wheelmold. the molten solder alloy is gravity fed from a vessel to'a' groove in the metal rirn of the wheel. and the solder rapidly cools and rapidly solidlfies in the grooveL'Th'e solidified solder continuous strip .5

strip will ordinarilf n otlbe worked aftferleavingithe wheel mold but ean'be worked. if desired. Theworking can be effected by cold working sach'as by compress-t ing in a press. suchas a vertical reeiproeating'press. or by rolling between the rolls of a eonventionairoiling apparatus. whereby th'e thickness of 'thesolde'r strip'is reduced 25% or more and usually in'the range of 25% to 75%.The solder strip ir-then cut into the desired length by IlCOllVOllllOlllll eutting blade. Alternatively. the liquid molten alley eanbe cut by static carting in the form ofbillett or pigs in a suitable'metalmoldQfor instance awater cooled copper mold. The billetsor pigs are extruded'intd filler 's'older'bars or strips of the desired cross-sectional dimensions andusually to re-- 'l'lte jd ata of theforegoing table shows that with tin con- 0.01% and 0.05% respectively. no tin-arsenic phase was present in the alloy. in Alloy No.s 5. 6. 8. 9. l3 and 14 wherein the total of arsenic plus antimony was in excess of 6% in ea'challoy. no dendritie lead. which is the rel ativelyhigh melting phase. was present and the sold'er is too liquid and'does not have the desired plasticity for 'applicatio'rtto automobile'bodies. in Alloy No. 4 wherein the total ofarsenic plus antimony was less than 3.5%. too much relatively high melting phase. i.e. 92% lead dendritel. is present in the alloy and insufficient low melting phase is present therein. and consequently there is too much volume fraction of soiidphase and too little volume fraction of liquid phase present in the alloy at 'the' application temperature in the range of 7 about 2459C. to about 285C.. and the solder is too solid and does not have the desired plasticity for application to automobile bodies at the aforementioned application temperatures. Further the liquidus temperature of Alloy No. 4 of 302C. is undesirably high. in Alloy No.s 7. i and i6. which are alloys of-this invention and wherein the total arsenic plus antimony is in the range of 3.5% to 6%. the alloys possess a proper ratio of volume fraction of solid phase (dendritic lead) to volume fraction of liquid phase at the application temperature in the range of about 245C. to 285C. to have the desired plasticity for easy. trouble-free application to automobile bodies.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a photomicrograph of a filler solder alloy of this invention which is free of tin as a constituent. the photomicrograph being at 200x magnification.

FIG. 2 is a photomicrograph of a filler solder alloy not of this invention and containing. by weight. 0.25% tin. the photomicrograph being at ZOOX magnification.

FiG. 3 is an electron image of a conventional filler solder alloy not of this invention and containing. by weight. i% tin. the electron image being at 400x magnification and obtained with a Scanning Electron Microscopc.

HO. 4 is a photomicrograph showing the large. hard tin-arsenic platelets which had been filtered out of a solder alloy not of this invention and containing 2% by weight tin. the photomicrograph being at'lX magnification.

FlG. 5 is a photomicrograph of a solder alloy not of this invention and containing4.90% by weight arsenic. the photomicrograph being at l00X magnification.

DETAILED DESCRIPTION Referring to FIG. 1 which shows the microstructure of a f ilier solder alloy of the present invention which is free of Sn as a constituent and contains, by weight 2% As. 2% Sb. balance Pb. the light-colored lead dendrites are shown at and the dark-colored low melting phases containing lead. arsenic and antimony at 11. With reference to FIG. 2 showing themicrostructure of a prior art fillersolder alloy and containing. by weight.'w

2% As. 2% Sb. 0.25% Sn. balance Pb. the undesirable "islands-like" tin-arsenic phase are shown at 12. the

light-colored lead dendrites at 10. and the dark-colored low melting phases at 11. Referring to FIG. 3 showing an electron image of the prior art filler solderalioy containing. by weight. 0.5% As. 5% Sb. 1.5%"Sn. balance Pb. a continuous network of theondesirable tin-arsenic phase in the form of hard platelets of the tin-arsenic phase. believed to be Sn. As is shown at 13. We found the hard platelets of the tin-arsenic phase when present in an extruded form or'shape of a rapidly cooled filler solder not of this inventionand containingin excess of.

micrograph of FIG. 4, a solder alloy containing. by

weight. 2% tin. 4% arsenic. 2% antimony, balance lead was melted and then filtered to filter out the'large hard tin-arsenic plateletsLThe separated .tin-arsenic plateiets. which retained some lead between the platelets. were subsequently remelted and cast in a mold. The

once to FIG. 5 showing an alloy containing. by weight. 4.90% arsenic. 2.l37r antimony, balance lead. antimony-arscnic crystals are shown at 15. secondary lead at 16 and other antimony-arsenic phases at 17. Antimonyarsenic crystals 15 are undesirable. large. hard crystals having typical largest dimension in excess of 0.001 inch. The presence of the large. hard antimony-arsenic crystals was attributed to the relatively large amount of arsenic. which was considerably in excess of the 2.5% upper limit of arsenic. The presence of these large. hard antimony-arsenic crystals is undesirable as they are believed to contribute to the grittincss problem which is overcome by the filler solder of the present invention. The alloys of H08. 1-5 were etched in a mixture of acetic acid and hydrogen peroxide prior to tal-ting the photomicrograph or electron image.

incidental impurities may be present in the solder alloys here. The incidental impurities are exemplified by one or more of copper. bismuth. silver. teiiurium. selenium and sulfur.

DESCRIPTION OF THE PREFERRED EMBODlMENTS The filler solder preferably has the following composition:

by Weight Antimony L5 to 5.3 Arsenic 0.7 to 2.5 Lead the remainder.

except for incidental impurities The total of arsenic plus antimony in the solder is at least 3.5% but not more than 6%. The microstructure of the solder is free of a tin-arsenic phase and free ofhard tin-arsenic platelets.

What is claimed is:

l. A filler solder containing essentially the following constituents in proportions within the proportion ranges hereafter set forth:

1' by Weight Antimony L5 to 5.3 Arsenic 0.7 to 2.5 Tin 0 to 0.20 Lead substantially the remainder the total arsenic plus antimony being at least 3.5% but not more than 6%. the solder being substantially free of hard tin-arsenic platelets and free of an undesirable grittiness due to elimination of the hard tin-arsenic platelets, the solder having a freezing range corresponding to a liquidus of about 285C. and a solidus of about 245C. and a plasticity at an application temperature within the about 245C. to about 285C. freezing rangesuch as to enable the solder plastic mass to be readily applied to an automobile body. .2. The solder of claim! containing. at the application temperature within the about 245C. to about 285C. range. about 70% to about by volume of dendritic lead and about 30% to about 20% by volume of liquid phase.

3. The solder of claim 2 wherein the solder is free of tin as a constituent.

4. The solder of claim 2 also containing a grain refining agent.

5. The. solder of claim 4 wherein the grain refining agent is sulfur.

6. The filler solder of claim 2 in the form of a bar.

t i i i I hard tin-arsenic platelets are shown at 14. With referg mm: C E R TI 55 Patent No. 3,923,501 Dat'e December 2, 1 975.

. Inventofls) Carl R. DiMartzini and Michael Myers It is certified that error appears-in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

.. Page 1, in the abstract, penultimate line thereofi "smoothsurfaced" should read smooth-surfaced Column 1, line 26, "of" should read or Column 2, lines 55 and 56, "elminated" should read eliminated Column 6, line 3, delete "a". Column 8, line 18, "here" should read herein t Signed and Sealed this first Day of June 1976 Q [SEAL] Anesr:

RUTH c. msou I c. MARSHALL DANN 6 Alresn'ng Officer Commissioner nflalems and Trademarks 

1. A FILLER SOLDER CONTAINING ESSENTIALLY THE FOLLOWING CONSTITUENTS IN PROPORTIONS WITHIN THE PROPORTION RANGES HEREAFTER SET FORTH:
 2. The solder of claim 1 containing, at the application temperature within the about 245*C. to about 285*C. range, about 70% to about 80% by volume of dendritic lead and about 30% to about 20% by volume of liquid phase.
 3. The solder of claim 2 wherein the solder is free of tin as a constituent.
 4. The solder of claim 2 also containing a grain refining agent.
 5. The solder of claim 4 wherein the grain refining agent is sulfur.
 6. The filler solder of claim 2 in the form of a bar. 